I. Field of the Invention
This invention relates to an impact beam assembly for a vehicle door and, in particular, to a hollow tubular beam with end mounting brackets which is designed for improved absorption of side vehicle impacts. The hollow beam body is manufactured using roll forming from a metal strip for economical manufacture.
II. Description of the Prior Art
In the continuing attempt to improve passenger safety in motor vehicles, side impact beams have been provided for use in the side passenger doors of automotive vehicles. Typically, the beams include structural steel members which extend between the fore and aft vertically extending walls of the vehicle door. In the past these structural steel members have been stamped from sheet metal into various cross-sectional configurations, most commonly a hat-shaped cross-section. Straight tubular beams with various end attachments are also used for these structural steel members. Despite striving for improved impact absorption, weight and cost consideration are also important to maintain the efficiency and economy of the vehicle.
Furthermore, federal vehicle safety standards specify that side door impact beams must meet certain load or energy absorbing criteria for a specified lateral displacement of the door in response to a vehicle being subjected to a side impact. While known side door impact beam assemblies used in vehicles produced in the United States have been satisfactory in use and have met these federal safety standards, there is a continuing effort to reduce the mass and/or cost of these assemblies without sacrificing protection or energy-absorption of these impact beam assemblies. In addition to the hat-shaped and straight tubular beam configuration most commonly used in vehicles, various configurations have been experimented with to improve the side impact beam. Changes to the hat-section and straight tubular shapes have not been commonly used because of the cost and difficulty of manufacturing.